diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0e741408..2a14e78f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,10 @@
+## 1.47.1
+
+### JS API
+
+* **Potentially breaking bug fix:** Match the specification of the new JS API by
+  setting `LegacyResult.map` to `undefined` rather than `null`.
+
 ## 1.47.0
 
 ### JS API
diff --git a/lib/src/node/legacy.dart b/lib/src/node/legacy.dart
index a4e32e49..ce3f0d56 100644
--- a/lib/src/node/legacy.dart
+++ b/lib/src/node/legacy.dart
@@ -357,7 +357,10 @@ RenderResult _newRenderResult(
   var end = DateTime.now();
 
   var css = result.css;
-  Uint8List? sourceMapBytes;
+  // TODO(nweiz): Get rid of this cast once pulyaevskiy/node-interop#109 is
+  // released.
+  // ignore: prefer_void_to_null
+  Uint8List? sourceMapBytes = undefined as Null;
   if (_enableSourceMaps(options)) {
     var sourceMapOption = options.sourceMap;
     var sourceMapPath =
diff --git a/pubspec.yaml b/pubspec.yaml
index d1d44633..70ff2bf1 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: sass
-version: 1.47.0
+version: 1.47.1-dev
 description: A Sass implementation in Dart.
 homepage: https://github.com/sass/dart-sass